The reconfigurable radio direction finder system and method uses a reconfigurable antenna to electronically cycle through a plurality of different antenna configurations to determine a signal direction. Specifically, the reconfigurable antenna is cycled through N different antenna configurations, where N is an integer greater than one, where each antenna configuration has a pointing direction associated therewith defined by an elevation angle θn of an n-th antenna configuration, where n is an integer between 1 and N, and an azimuthal angle φn of the n-th antenna configuration. A received signal strength of the radio signal is measured for each of the antenna configurations as a power output of the n-th antenna configuration, Pn. A spherical weighted directional mean vector (XDF, YDF, ZDF) is then estimated for the radio signal as
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1. A reconfigurable radio direction finder system, comprising: a substrate; a planar array of patch antennae mounted on the substrate, wherein the planar array of patch antennae are arrayed in a rectangular grid having horizontal rows and vertical columns; and a plurality of switches connecting each of the patch antennae to horizontally and vertically adjacent ones of the patch antennae to form a reconfigurable antenna, wherein individual ones of said plurality of switches are selectively opened and closed to form a corresponding antenna configuration of the reconfigurable antenna, wherein the reconfigurable antenna is electronically cycled through N different antenna configurations, where N is an integer greater than one, wherein each said antenna configuration has a pointing direction associated therewith defined by an elevation angle θ n of an n-th antenna, where n is an integer between 1 and N, and by an azimuthal angle φ n of the n-th antenna, configuration, a set of received signal strength measurements and associated pointing directions being measured and saved such that an estimate of a spherical weighted directional mean vector for a radio signal, (X DF , Y DF , Z DF ) for first and second operational modes, is estimated as X DF = 1 N ∑ n = 1 N P n cos ( ϕ n ) sin ( θ n ) , Y DF = 1 N ∑ n = 1 N P n sin ( ϕ n ) sin ( θ n ) and Z DF = 1 N ∑ n = 1 N P n sin ( θ n ) , where P n is a power output corresponding to a measured, received signal strength of the radio for the n-th antenna configuration.
A radio direction finder system uses a reconfigurable antenna array on a substrate to determine the direction of a radio signal. The antenna array consists of patch antennae arranged in a rectangular grid. Switches connect each antenna to its horizontal and vertical neighbors, allowing the system to electronically cycle through different antenna configurations. For each configuration (N total), the system measures the received signal strength (Pn) and associates it with an elevation angle (θn) and azimuthal angle (φn). The system then calculates a spherical weighted directional mean vector (XDF, YDF, ZDF) to estimate the signal direction using the formulas: XDF = (1/N) * Σ (Pn * cos(φn) * sin(θn)), YDF = (1/N) * Σ (Pn * sin(φn) * sin(θn)), and ZDF = (1/N) * Σ (Pn * sin(θn)).
2. The reconfigurable radio direction finder system as recited in claim 1 , wherein each of the switches is a micro-electromechanical switch.
The reconfigurable radio direction finder system, which uses a reconfigurable antenna array on a substrate to determine the direction of a radio signal, uses micro-electromechanical (MEMS) switches to connect each antenna to its horizontal and vertical neighbors. This allows the system to electronically cycle through different antenna configurations. For each configuration (N total), the system measures the received signal strength (Pn) and associates it with an elevation angle (θn) and azimuthal angle (φn). The system then calculates a spherical weighted directional mean vector (XDF, YDF, ZDF) to estimate the signal direction using the formulas: XDF = (1/N) * Σ (Pn * cos(φn) * sin(θn)), YDF = (1/N) * Σ (Pn * sin(φn) * sin(θn)), and ZDF = (1/N) * Σ (Pn * sin(θn)). Using MEMS switches enables precise and fast reconfiguration of the antenna array.
3. The reconfigurable radio direction finder system as recited in claim 1 , wherein each of the switches is a radio frequency field effect transistor switch.
The reconfigurable radio direction finder system, which uses a reconfigurable antenna array on a substrate to determine the direction of a radio signal, uses radio frequency field effect transistor (RF FET) switches to connect each antenna to its horizontal and vertical neighbors. This allows the system to electronically cycle through different antenna configurations. For each configuration (N total), the system measures the received signal strength (Pn) and associates it with an elevation angle (θn) and azimuthal angle (φn). The system then calculates a spherical weighted directional mean vector (XDF, YDF, ZDF) to estimate the signal direction using the formulas: XDF = (1/N) * Σ (Pn * cos(φn) * sin(θn)), YDF = (1/N) * Σ (Pn * sin(φn) * sin(θn)), and ZDF = (1/N) * Σ (Pn * sin(θn)). Using RF FET switches enables high-frequency switching and signal integrity.
4. The reconfigurable radio direction finder system as recited in claim 1 , wherein an estimated elevation angle Ξ DF and an estimated azimuthal angle Φ DF of the radio signal are respectively determined as Ξ DF = cos - 1 ( z DF ( X DF ) 2 + ( Y DF ) 2 + ( Z DF ) 2 ) and Φ DF = tan - 1 ( Y DF X DF ) .
The reconfigurable radio direction finder system, which uses a reconfigurable antenna array on a substrate to determine the direction of a radio signal and calculates a spherical weighted directional mean vector (XDF, YDF, ZDF) to estimate the signal direction, further refines the signal direction estimate by calculating an estimated elevation angle (ΞDF) and an estimated azimuthal angle (ΦDF). These angles are calculated as follows: ΞDF = cos-1(ZDF / sqrt(XDF2 + YDF2 + ZDF2)) and ΦDF = tan-1(YDF / XDF). These calculations provide a precise 3D direction of the incoming radio signal, based on the previously calculated directional mean vector.
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July 7, 2014
November 14, 2017
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